In an electric vehicle, or a hybrid vehicle operating in the electric mode, an electric motor serves as the source of power for the vehicle. In such vehicles, a battery provides power to drive the motor to produce torque. An inverter coupled to the motor directs current to the motor to produce torque in response to a torque request by a driver of the vehicle. The driver controls the position of the accelerator and brake pedals to request different amounts of torque from the motor. When the driver presses down on (or depresses) the accelerator pedal, a powertrain controller detects the position of the pedal and sends a signal to the inverter/motor controller to increase the torque produced by the motor. When the driver releases the accelerator pedal and/or presses down on the brake pedal, the power train controller sends a signal to the motor/inverter controller to decrease the motor torque. Based on the accelerator and brake pedal positions, the powertrain controller generates a torque request signal which is directed to the motor/inverter controller which actuates the motor to produce the requested torque.
For any given motor speed, there exists an optimum value (or region) of output torque that results in maximum motor efficiency. An efficiency graph (or iso-efficiency plots) for a motor, includes curves of the motor efficiency for different rotational speeds and torque values. Since the torque output of an electric vehicle motor at any instant is determined based on the driver's request, the operating condition of the motor at that instant may not be optimal. The current disclosure provides systems and methods of controlling the electric motor of the vehicle that may alleviate the concern discussed above. The scope of the current disclosure, however, is defined by the attached claims, and not by the ability to solve any specific problem.